Zero-Crossing Detection Circuit With Shortened Optocoupler Conduction
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Solution Overview
Problem
Existing zero-crossing detection circuits for AC systems are power-intensive due to large energy storage capacitors and prolonged charging times, which affects detection accuracy and component lifespan.
Innovation Solution
A zero-crossing detection circuit design that includes a photoelectric coupler, an optocoupler driving module, and an energy storage capacitor with current-limiting resistors and voltage clamp modules, reducing the conduction interval of the photoelectric coupler to minimize power consumption and enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a large capacitance energy storage capacitor is used to control optocoupler conduction, then the optocoupler can maintain conduction longer, but the charging time increases and power consumption increases
Solution Approach 1:
The patent implements periodic action by using the alternating current signal to periodically charge and discharge the energy storage capacitor. The capacitor is charged during positive half-cycles and discharged during negative half-cycles, creating a rhythmic conduction pattern that reduces average power consumption while maintaining necessary detection duration. This periodic operation allows the system to achieve the required conduction duration without requiring a large capacitor that would consume excessive power continuously.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the conduction interval of the optocoupler based on the alternating current signal characteristics. By changing the conduction timing to coincide with signal zero-crossings and by adjusting the capacitor charge/discharge cycle to match the AC frequency, the system optimizes both the duration of action and power consumption. The parameter optimization shows that shorter, more frequent conduction intervals are more efficient than prolonged continuous conduction.
2Duration of action of moving object
If a large capacitance energy storage capacitor is used, then the optocoupler can maintain conduction, but the charging time becomes longer
Solution Approach 1:
The patent uses periodic action synchronized with the AC signal frequency to charge the capacitor in short intervals during each positive half-cycle, rather than attempting to charge a large capacitor in one long interval. This periodic charging approach allows the system to maintain optocoupler conduction through repeated short charge cycles, significantly reducing the time loss associated with charging while maintaining the necessary duration of action for detection.
3Reliability
If the photoelectric coupler conduction interval is extended, then detection coverage is improved, but power consumption increases and component lifespan decreases
Solution Approach 1:
The patent implements periodic action by restricting optocoupler conduction to specific intervals synchronized with the AC signal cycles, particularly around the zero-crossing points. This periodic conduction pattern ensures that detection coverage is maintained at critical moments while avoiding continuous conduction that would waste energy and reduce component lifespan. The system achieves reliable detection by focusing conduction effort on the most critical detection intervals.
Solution Approach 2:
The patent applies the extraction principle by removing unnecessary portions of the conduction interval, keeping the optocoupler active only during the critical zero-crossing detection periods rather than maintaining continuous conduction. This extraction of excess conduction time reduces power consumption and thermal stress on components while preserving the essential detection function, thereby improving both energy efficiency and component reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces average power consumption and prolongs the service life of circuit components while maintaining high zero-crossing detection accuracy by shortening the photoelectric coupler's conduction period.
Implementation Method 1
an photoelectric coupler, connected to the zero-crossing judgment module
Data Source
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AI summary
The present disclosure discloses a zero-crossing detection circuit, including: a zero-crossing judgment module, having a first end and a second end, wherein the first end is connected to a power supply and the second end is grounded; a photoelectric coupler, connected to the zero-crossing judgment module; an optocoupler driving module, connected to the photoelectric coupler; and an energy storage capacitor, wherein the energy storage capacitor is configured to provide excitation power for the photoelectric coupler and the optocoupler driving module. The technical solutions of the present disclosure reduce the conduction interval of the photoelectric coupler in the circuit, not only reducing the average power consumption of the circuit and prolonging the service life of the circuit components, but also enabling high zero-crossing detection accuracy.